Volatile cleaning composition

ABSTRACT

AA NEW SURFACE CLEANER THAT IS SUBSTANTIALLY COMPLETELY VOLATILE, RREQUIRES NO SURFACE RUBBING, CAN BE UTILIZED IN A PRESSURIZED CONTAINER, A DEGREASING OR ULTRASONIC CLEANING TANK, A PUMP DISPENSER OR OTHER LIQUID DELIVERY AND DISPENSING SYSTEMS. AND COMPRISES TWO OR MORE READILY VOLATILIZABLE ALCOHOLS IN SOLUTION WITH A SURFAACE ACTIVE AGENT AND A GREASE SOLVENT. WHEN PACKAGED IN PRESSURIZED CONTINERS OR PUMP DISPENSERS, THE CLEANER IS CAPABLE OF BEING SPRAYED AS A LIQUID ONTO THE SURFACE TO BE CLEANED. CLEANING THAT SURFACE, AND COMPLETELY EVAPORATING. THEREBY ELIMINATING THE NEED FOR RUBBING OR WIPING THE WORKPIECE SURFACE AND MAKING THE CLEANER PARTICULARLY APPLICABLE TO OPTICAL LENS SURFACES. THE FORCE GENERATED IN EXPELLING THE FORMULATION FROM THE PRESSURIZED CONTAINER SPREADS THE FORMULATION OVER THE SURFACE, LOOSENING AND DISLODGING PAARTICLES OF DIRT AND DUST THEREON WHILE DISSOLVING OILS, WAXES, SALTS-ORGANIC AND INORGANIC SURFACE CONTAMINANTS. THE VOLUME AND VELOCITY OF THE DELIVERED SPRAY SLUICES AND CARRIES AWAY ALL DISLODGED AND DISSOLVED MATERIALS TO THE LOWEST POINT ON THE SURFACE BEING CLEANED, LEAVING ONLY A THIN UNIFORM FILM OF THE CLEANING FORMULATION EVENLY SPREAD OVER THE SURFACE, WHICH THEN EVAPORATES SUBSTANTIALLY COMPLETELY, LEAVING NO VISIBLE RESIDUAL FILM OR SPOTS. WHEN THE CLEANING COMPOSITION IS CONTAINED IN A DEGREASING OR ULTRASONIC CLEANING TANK, THE SURFACE TO BE CLEANED IS DIPPED INTO THE SOLUTION AND, UPON WITHDRAWAL OF THE SURFACE FROM THE TANK, THE CLEANER WILL EVAAPORATIVELY RUN OFF CARRYING AWAY THE DISSOLVED ORGANIC AND INORGANIC SUBSTANCES WITH IT, LEAVING A CLEAN, RESIDUE-FREE SURFACE.

I APPROX. vAPoR PR A ril 17, 1973 Filed March 23, 1970 U) OO VAPORPRESSURE (mm Hg) N G. M. STEPHENSON ET AL VOLATILE CLEANING COMPOSITION2 Sheets-Sheet 1 METHANOL ETHANOL n-PROPYL ALCOHOL WATER E 2-METHOXY-ETHANOL 5 IO IS so as 4s 7 so 6 5 7'5 TEMPERATURE 3-, HO N H at o O oESSURE in mm. of b 01 METHANOL ETHANOL L n-PROPYL ALCOHOL ETHANOL/3,5-D|METHY L- 1-HEXYN-3-OL 20 30 4o 50 6'0 7'0 8'0 9b IOO INVENTORSGEORGE M. STEPHENSON JOHN FRANGOS MATTER/V WARE 8 DAV/5 ATTORNEYS p 17,1973 G. M. STEPHENSON E AL 3,728,269

VOLATILE CLEANING COMPOSITION Filed March 23, 1970 2 Sheets-Sheet 2 HEATSUPPLIED TO COMPENSATE FOR EVAPORATIVE COO-LING l l l j l l I lTEMPERATURE IN c 3,728,269 VOLATILE CLEANING COMPOSITION George M.Stephenson, Wilton, Conn., and John Frangos,

New York, N.Y.; said Frangos assignor to said Stephenson Filed Mar. 23,1970, Ser. No. 21,725 Int. Cl. C09d 9/04; Clld 2/50; C23g 5/02 U.S. Cl.252-171 1 Claim ABSTRACT OF THE DISCLOSURE A new surface cleaner that issubstantially completely volatile, requires no surface rubbing, can beutilized in a pressurized container, a degreasing or ultrasonic cleaningtank, a pump dispenser or other liquid delivery and dispensing systems,and comprises two or more readily volatilizable alcohols in solutionwith a surface active agent and a grease solvent. When packaged inpressurized containers or pump dispensers, the cleaner is capable ofbeing sprayed as a liquid onto the surface to be cleaned, cleaning thatsurface, and completely evaporating, thereby eliminating the need forrubbing or wiping the workpiece surface and making the cleanerparticularly applicable to optical lens surfaces. The force generated inexpelling the formulation from the pressurized container spreads theformulation over the surface, loosening and dislodging particles of dirtand dust thereon while dissolving oils, waxes, salts-organic andinorganic surface contaminants. The volume and velocity of the deliveredspray sluices and carries away all dislodged and dissolved materials tothe lowest point on the surface being cleaned, leaving only a thinuniform film of the cleaning formulation evenly spread over the surface,which then evaporates substantially completely, leaving no visibleresidual film or spots. When the cleaning composition is contained in adegreasing or ultrasonic cleaning tank, the surface to be cleaned isdipped into the solution and, upon withdrawal of the surface from thetank, the cleaner Will evaporatively run off carrying away the dissolvedorganic and inorganic substances with it, leaving a clean, residue-freesurface.

BACKGROUND OF THE INVENTION The present invention relates to new,surface cleaning compositions and more particularly to volatile,non-rubbing, optical lens cleaners, packaged in suitable containers.

Many different cleaning formulations have been used in the past forcleaning surfaces such as glass, walls, woodwork, plastics, etc. Thesecompositions generally contain a detergent. After being applied to cleana surface such as glass, generally by scouring, rubbing or abrasiveaction, they leave a film behind which acts as a trap for dirt and dustparticles, and interferes with the optical preciseness of finely groundlenses.

Many attempts have been made to produce volatile cleaning or detergentcompositions which will completely evaporate after performing thecleaning function and will leave no residual film. Volatile compositionswhich leave no residual film are available; however, they are notcapable of adequately cleaning substantially all types of contaminationthat may be found on the surface of a workpiece.

Furtherfmore, most volatile cleaning compositions contain a combinationof alcohol and water. Because of the high surface tension of water,these cleaning compositions, after spreading over the surface to becleaned, coalesce in small droplets or globules. As the solventevaporates from the surface to be cleaned, the water-soluble 3,728,269Patented Apr. 17, 1973 dirt concentrates in these droplets and causessurface rings, or spotting.

The limitations of presently existing surface cleaners create severeproblems in cleaning finely ground optical lenses, and other surfacesand materials. Because of the high standards to which these lenses aremanufactured and the precision required in their use, both rubbing andspotting should be completely avoided. If an optical lens is rubbed evenby delicate fibers, fabrics or tissues during the cleaning process,there is a possibility that the surface will be scratched by anentrained abrasive particle and thus the lens efficacy will be reduced.Furthermore, if residual films or spots remain on an optical lens aftercleaning, designed light transmission and refraction characteristics aredegraded.

Therefore, an object of this invention is to provide a cleaningcomposition having effective cleaning capability, while leaving noresidual film on the surface after cleanmg.

A further object of this invention is to provide a cleaning compositionwhich Will evaporate substantially completely after its cleaningfunction has been performed.

Another object of this invention is to provide a cleaning compositionthat completely eliminates the need for rubbing.

A further object of this invention is to provide a cleaning compositionthat can be easily applied to any surface by means of various liquiddelivery and dispensing systems, such as pump dispensers.

Another object of this invention is to provide a cleaning compositionthat spreads over the entire surface to be cleaned in a continuous tfilmand thereby eliminates globular or fish eye formations and resultingspots.

Another object of this invention is to provide a cleaning compositionthat can be easily applied to any surface by spraying the compositionfrom a pressurized container.

A further object of this invention is to provide a cleaning compositionthat contains minimal water.

Another object of this invention is to provide a cleaning compositionthat is capable of delivery in a high volume stream directed toward thesurface to be cleaned, thereby dislodging and carrying away particles ofdirt and dust which otherwise could not be removed during the cleaningoperation without risk of scratching or marring the lens surface.

Another object of this invention is to provide a cleaning compositionthat is capable of being applied to many smooth impervious surfaces,such as metals and plastics.

Other and more specific objects will be apparent from the features,elements, combinations and operating procedures disclosed in thefollowing detailed description and shown in the drawings.

SUMMARY OF THE INVENTION This invention relates to the formulation of anew, completely volatile, low water content cleaning compositioncomprising varying amounts of two or more readily volatilizable alcoholsas the major proportion of its ingredients and at least one volatilesurface active agent, and which is utilized in a pressure dispensing orpump dispensing system, in an ambient pressure degreasing or ultrasonictype tank, or in other liquid delivery and dispensing systems. The useof a substantially completely volatile, low water content cleaningcomposition packaged in a pressurized container provides an extremelyeffective optical lens cleaner capable of first dislodging and carryingaway foreign particles accumulated on the surface and, secondly, capableof dissolving and removing films of the usually encountered types ofgrease, oil, wax and salt deposits Without leaving any residual film orspots. All of the compounds used in the cleaning formulation aresubstantially volatile and substantially anhydrous.

In a tank, the surface to be cleaned can be dipped or maintained in thecleaning composition to dissolve the organic and inorganic surfacecontaminants; and, after removal from the tank and evaporation of thecleaning composition, the surface will be adequately clean, residue freeand spotless. In this method of use it is desirable to employ two orthree such tanks and to transfer the items to be cleaned in the sameorder from tank to tank so that the final dip will be with a soil-freecleaning composition.

The compositions of this invention achieve these objectives bysubstantially reducing water and including a volatile surfactant and avolatile grease solvent in addition to different alcohols havingdifferent volatility rates to form the major proportion of the cleaningcomposition, all packaged in a pressurized container having a valvecontrolled outlet. A cleaning composition is thus created that iscapable of being applied at different cations to any surface to becleaned and which washes away dirt and dust particles upon contact withthe surface, dissolves most common inorganic and organic substances,spreads evenly over the entire surface, evaporates in a controlledgraduated manner, and thus leaves no visible residual films or spots.

THE DRAWINGS FIG. 1 is a graph showing the relationship of the vaporpressures of the alcoholic constituents utilized in this invention as afunction of temperature as compared to that of water.

FIG. 2 is a diagrammatic representation of the graduated volatility ofthe components of a preferred cleaning formulation according to theinvention.

FIG. 3 is the test results of a Differential Scanning Calorimetershowing the additional heat supplied to the preferred composition ofthis invention to compensate for evaporative cooling.

SPECIFIC DESCRIPTION The present invention utilizes a mixture of atleast two volatile alcohols and at least one volatile surface activeagent. The surface active agent must be miscible or soluble in thealcoholic mixture and may be one or more of the group consisting ofwetting agents, detergents or grease solvents. These agents maythemselves be readily volatilizable or may be volatilizable as a resultof their solution in the alcoholic component.

The alcoholic component employed herein must be readily volatilizable atambient pressure and temperature, i.e., atmospheric pressure and atemperature of not more than 80 F. Essentially included are methanol orethanol, or both, which readily vaporize at ambient conditions, methanolbeing preferred in all compositions as will be pointed out hereinafter.In addition, the propanols (preferably n-propyl alcohol) and unsaturatedalcohols of 3-5 carbon atoms may be employed because of the miscibilityof such alcohols and the tendency of the mixtures to form highlyvolatile azeotropes which will evaporate rapidly and completely.

Generally, the alcoholic component will comprise 70-99 percent by weightof the composition and the surface active agents will comprise 1-30percent by weight of the composition. Of the alcoholic component, atleast percent by weight thereof should comprise methanol and/ orethanol; preferably they should comprise at least percent by weightthereof. The preferred alcohols are anhydrous or substantially anhydroussince water is considered detrimental to optimum operation. However,absorption of water in methanol and ethanol is difficult to avoid;accordingly, up to 8 percent by weight thereof and preferably not morethan 5 percent may in practice be comprised of water.

If the surface active agents is comprised of components all havingrelatively low volatility, they should comprise not more than 10 percentby weight of the composition and preferably less than 5 percent. Whenthe surface active agent is comprised at least principally of acomponent which vaporizes readily at ambient temperature and pressure,it may comprise up to 30 percent by weight of the composition althoughit is preferably less than 15 percent. The surface active agents includegrease solvents such as glycol ethers and dialkyl ethers, both havingless than 6 carbon atoms. Detergents having a relatively high degree ofvolatility which also function as surface active agents to promoteuniform wetting are highly advantageously employed; thealkyl-substituted alkyn-ols having up to 12 carbon atoms and preferably6-9 carbon atoms being exemplary thereof. Other relatively volatilecompounds exhibiting surface active propetries may also be employed suchas C -C esters of C -C organic acids.

The preferred embodiment of this cleaning formulation uses threealcohols, methanol, ethanol and n-propyl alcohol, to form 94-98% byweight of the cleaning composition. It is apparent to one skilled in theart, however, that this cleaning composition could be effective by usingonly two alcohols; preferably, eliminating the ethanol. The inclusion ofmethanol is important since methanol acts as a solvent for many of theusual inorganic substances on the surface to be cleaned and carries themaway by draining. The ethanol is used in the preferred embodiment sinceit is capable of dissolving both inorganic and organic substances, endserves to provide an evaporative bridge between the higher volatility ofmethanol and the comparatively lower volatility of the n-propyl alcohol.The ethanol will also dissolve inorganic substances and some of thelighter organic substances. The n-propyl alcohol has vapor pressure nearthat of water and is the last alcohol to evaporate. ,Since the heavierorganic soils are frequently more difiicult to dissolve, the use ofn-propyl alcohol provides assurance that the stubborn heavier organicsubstances will be dissolved and carried away by drainage.

The remaining 26% of this preferred cleaning formulation comprises 13%by weight of a volatile surfactant, capable of performing as both awetting agent and a detergent, preferably 3,5-dimethyl-1-hexyn-3-ol, andl-3% by Weight of a grease solvent in the glycol ether family,preferably 2-methoxy-ethanol. The use of a grease solvent provides addedassurance that all of the heavier organic substances will be removedfrom the surface and dissolved in the alcohols prior to theirevaporation. The surfactant serves a two-fold purpose since it acts as adetergent which gives the formulation an added cleaning ability, andalso performs as a wetting agent to assure that the cleaning compositionwill completely and uniformly spread over the entire surface to which itis applied.

The preferred embodiment of this cleaning composition is as follows:

TABLE I Percent by weight Range Preferred In FIG. 1, the vapor pressuresof the major constituents in the preferred formulation are plotted as afunction of temperature. The vapor pressure of water as a function oftemperature is represented by the dotted line. By referring to FIG. 1and Table 1, it can be seem that 96% of the preferred formulation has avapor pressure which is greater than or very similar to that of Water.Since the volatility of a particular substance is directly related tothe substances vapor pressure, it is reasonable to expect barring theexistence of azeotropes, that each portion evaporating from the film ofmixed solvents will be richer in the more volatile solvent, thus thelast portion evaporating will be richest in the least volatile solvent.However, even if azeotropes were to form causing the less volatilematerial to be in part volatilized with the more highly volatilematerial; nevertheless, some degree of stepwise volatilization wouldtake place. The ideal, controlled, graduated volatility of the preferredcleaning formulation as it would evaporate from the surface to which itwas applied if no azeotropes were formed is diagrammatically representedin FIG. 2. The step that represents 3,5-dimethyl-l-hexyn-3-ol is shownby a dotted line since the vapor pressure was estimated. In reality theevaporation proceeds in a three-stage process as represented in FIG. 3.

The curve shown in FIG. 3 was generated by Warming the preferredformulation in a Differential Scanning Calorimeter, Perkin-Elmer ModelDSC-IB. The Differential Scanning Calorimeter contains two pans, asample pan and a control or empty pan. The device records the heat thatmust be supplied to the sample pan to maintain both pans at the sametemperature.

The curve shown in FIG. 3 was generated by placing the preferredformulation in the sample pan and leaving the second pan dry. Both panswere raised to increasing temperatures at the rate of 1.25 C. per minutefrom about 29 C. to about 39 C. The curve of FIG. 3 records theadditional heat reqlired to raise the sample pan temperature througheach temperature increment, as compared to the heat needed to raise thedry control pan by the same increment of temperature. The test resultsshown in FIG. 3 are thus believed to reflect significant fluctuatrons inthe rate of evaporation of the composition with mcreasing temperature,and strongly suggest, as do visual tests, that the evaporative processoccurs in three successive, recognizable steps or stages. Line segment21 is a smooth curve until the point of inflection 30 is reached. Theslope change there, between line segment 21 and the next lme segment 22apparently represents a change in the heat of vaporization taking placein the pan containmg the preferred formulation.

Line segment 22 is a steeper, smooth curve until the next point ofinflection 31 is reached at which time line segment 23 follows with asignificantly different slope than line segments 21 or 22. The durationof the test was approximately 8 minutes, but when the solution is spreadonto a surface, the liquid depth is much less than it 'Was in the testpan, and the formulation normally completely evaporates in 23 minutes.

It is believed that during the first stage most of the methanolevaporates, after carrying off the inorganic substances by gravity flow,and also most of the ethanol evaporates after carrying off inorganic andsome organic substances by gravity flow. In the second stage, anyremammg methanol and ethanol are believed to evaporate and and then-propyl alcohol also evaporates after removmg organic surfacecontaminants by gravity flow.

The last stage is charcterized by a visible haze, that appears and thenslowly disappears; it is believed that this is the evaporation of theremaining 2-methoxy-ethanol and 3,5-diamethyl-1-hexyn-3-ol. At the endof two to three minutes, the surface is clean, has no dirt spots, andshows no visible residual film.

Even if the proposed three-stage evaporation process does not in factoccur, the judicious selection of solvents and surfactants, which havethe capability of dislodging, deterging or dissolving the soils, aresubstantially volatile and free of non-volatile impurities and thereforedo not leave deposits, are substantially water-free and have low surfacetensions and different vapor pressures, does create a cleaningcomposition that is capable of being applied to substantally anysurface, either by utilizing a pressurized container or by immersion inan ultrasonic or conventional cleaning or degreasing tank, completelycleaning that surface by removing not only dust and dirt particles butalso commonly encountered inorganic and 6 organic contaminants andleaving a residue-free, spotless surface.

Furthermore, the proper selection of one or more volatile solvents whosevapor pressure is less than that of water avoids severe evaporativecooling effects. Generally, upon application of the cleaningcomposition, the surface of the workpiece is cooled to a temperaturebelow the dew point and causes moisture condensation. By selectingsolvents that have vapor pressures less than water and, also, aresolvents for water, during the final stages of drying the condensedwater will be dissolved in the solvent that are capable of uniformlywetting the surface. This prevents the condensation water from coatingthe surfaces, during drying, in the form of discrete droplets, orfish-eyes, with minute traces of particulate matter suspended anddissolved within, and leaving said particulate matter behind afterdrying in characteristic, spot-lke, visible patterns.

Abrupt evaporative cooling, condensed water droplets, isolated separatefish-eye drops of independently evaporating solvent, and deposits orresidual films of contaminants and impurities left behind by evaporatingsolvent are all substantially eliminated by the formulations of thisinvention, whether or not a step-like evaporation process occurs.

For these reasons, tests have shown the formulation dlS- cussed above tobe the preferred one for a non-rubbing lens cleaning composition. It ispossible, however, to vary the substances used in this formulation andstill obtain a cleaning composition that will perform adequately. Theranges over which the preferred substances can be varied are shownbelow:

TABLE 11 Percent by weight Methanol 15-50 Ethanol 0-25 Z-methoxy-ethanol0-4 3,5-dimethyl-1-hexyn-3-ol 0-4 n-Propyl alcohol: Comprising theremainder, preferably at least 25%.

In using this table of ranges it is important to remember the purposefor which each of the substances is included. It would be unwise toformulate a cleaning composition that used the maximum for all thesubstances and thereby left n-propyl alcohol at its absolute minimum of17% by weight. The n-propyl alcohol is required to dissolve and removethe heavy organic substances on the surface. Since the heavy organicsubstances resist dissolution to a greater extent than the inorganicsubstances, it is imperative that a suflicient amount of n-propylalcohol is present in the formulation so that removal of all organicsubstances will be assured. Consequently, when the methanol content isincreased to its upper limit, the ethanol content should be decreased.

It would be possible to formulate a cleaning composition that employsthe teachings of this disclosure without using all of the compoundssuggested herein or by using substites. One example of possiblesubstitutes would be to use other glycol ethers in place of2-methoxy-ethanol. In place of 3,5-dimethyl-l-hexyn-3-ol, any othervolatile surfactant or combination of volatile surfactants which iscapable of performing as both a detergent and a wetting agent could beemployed. Furthermore, isopropyl alcohol may be substituted for n-propylalcohol. Small amounts of non-volatile surfactants may be employedprovided that they leave continuous optically acceptable film residues,for example dioctyl ester of sodium sulfosuccinic acid. Examples ofsubstitute cleaning compositions are shown in Tables III and IV.

TABLE III Percent 'by weight Methanol 2.0

Ethanol 16.67

n-Propyl alcohol 79.3 2-butoxy-ethanol 1.0 3,5-dimethyl-l-hexyn-3-ol 1.0Diocetyl ester of sodium sulfosuccinic acid 0.03

TABLE IV Percent by weight Methanol 2.0

Ethanol 16.67 n-Propyl alcohol 46.0 Isopropyl alcohol 33.32-butoxy-ethanol 1.0 3,5-dimethyl-l-hexyn-3-ol 1.0 Dioctyl ester ofsodium sulfosuccinic acid 0.03

These cleaning compositions would be suitable substitutes for thepreferred formulation in applications where an optically clear filmwould be permissible.

Extensive testing has been performed using isopropyl alcohol, and it wasdiscovered that isopropyl alcohol left a slight residue uponevaporation. For that reason, isopropyl alcohol has not been included inthe preferred embodiment of this cleaning composition. If, however, aresidue-free isopropyl alcohol were available, it could easily besubstituted for the n-propyl alcohol.

The importance of the advantage that is achieved by providing aformulation for a cleaning composition is substantially free of waterwas clearly observed in the testing of this formulation, wherein anexperimental batch was made which contained 1% by weight of water. Afterapplication to the surface to be cleaned and evaporation, it wasobserved that the surface contained dirt spots. By using the preferredembodiment of this cleaning composition, which is substantially withoutwater, a clean, residuefree, spotless surface was obtained.

The eflicacy of this cleaning composition is enhanced by delivery underpressure to provide a soil displacement force by packaging theformulation in a pressurized container or pump dispenser having a valveactuated discharge outlet. In a convenient embodiment the formulation ispackaged under pressure in an aerosol-type pressurized container with apropellant, preferably dichlorodifluoromethane. This unique systemprovides a two stage cleaning operation for any surface to which it isapplied. In the first stage the particles of dust and dirt are dislodgedand sluiced away by the application of the formulation to the surface.This self-flushing action is accomplished by the forces produced inpropelling the formulation toward the surface to be cleaned. As thecleaning composition impacts upon the surface to which it is applied,the spray dislodges and sluices away the nonsoluble particles of dustand dirt.

The second cleaning stage is achieved by the cleaning composition itselfas it uniformly spreads over the entire surface to which it is appliedand dissolves and carries away by gravity flow inorganic and organicsubstances on the surface, without leaving any visible residual film orspots. This arrangement provides a self-flushing, self-cleaning,completely evaporative, non-wiping lens cleaner, leaving a residue-free,spotless surface.

The cleaning operation is accomplished by remote application and withoutever having to touch the surface to be cleaned with anything except thecleaning composition. The tests that have been performed on the surfacecleaner formulated according to this invention have proven that normallysoiled surfaces can be cleaned by a single application of this surfacecleaner without manual contact with the surface. Furthermore, heavilysoiled surfaces have also been cleaned by this surface cleaner by onlyseveral applications of the surface cleaner, and Without manual contact.

These cleaning compositions have been found to be compatible with manymaterials. While the cleaning of optical lens surfaces was the principalobjective in the formulation of these cleaning compositions, theirefiicacy is not limited to lens surfaces; the compositions of thisinvention are highly effective in cleaning many different materials.

The preferred embodiment for the surface cleaner comprises packaging theformulation previously described with dichlorodifluoromethane as thepropellant in such a manner that the pressurized container will containabout by weight of the formulation and about 15% by weight of thepropellant. This has been prove to be an effective ratio to providesufficient force for stage one dislodging cleaning. The kind and amountof propellant used, however, can be greatly varied since it is dependentupon other surrounding conditions. The propellant content and type ofpropellant can be varied in accordance with the delivery force desiredor the type of spraying effect that is sought. Furthermore, for everydifferent discharge outlet used the propellant may be altered in orderto achieve the propelling and spraying conditions desired.

It is important to note that difficulties that have existed inpre-existing cleaning compositions are eliminated by this surfacecleaner. This surface cleaner not only dislodges and sluices awaysurface dirt and dust particles upon application, but then uniformlyspreads over the surface to which it is applied, and dissolves inorganicand organic substances. It is believed that as the formulationevaporates, it retreats as a single body of liquid to the lowest pointof the surface to which it was applied with the retreating rear edge ofthis liquid body pushing ahead of itself and carrying with it thedissolved contaminants, leaving a clean, residue-free, spotless surfacewithout any requirement for rubbing, polishing or additional orsupplemental contact with the surface.

The major difficulties with conventional surface cleaners are the needfor rubbing the surface to achieve adequate cleanliness, and theexistence of a residual film and spots on the surface after the cleanerhas evaporated. Many of these prior art difiiculties are eliminated inthis invention b using methanol in addition to one or more other readilyvolatile solvents and substantially completely eliminating the use ofwater, other than that present as a trace impurity.

Spotting results from the cleaners that contain appreciable waterbecause the high surface tension of Water causes the cleaningcomposition to distribute itself over the surface in numerous globularor fish-eye, formations during drying. As the cleaning compositionevaporates, trace insolubles and particles picked up from the atmospherebecome increasingly concentrated in each globule or fish-eye, and afterfinal drying remain on the surface as dirt spots. By using solvents oflow surface tension, the formulation of this invention does not formglobules upon application to a surface or during drying, but insteadspreads evenly over the entire surface to be cleaned and remains as asubstantially uniform film throughout the drying period. Although notcompletely necessary, the preferred embodiment of this inventionincludes a wetting agent to further enhance the complete spreadabilityof this formulation. By eliminating globular or fish-eye formation, dirtspots are substantially eliminated.

The second advantage achieved by this invention is the elimination ofthe need for any rubbing of the surface at all. Rubbing with tissues,swabs, lens cleaning cloths or any other medium is dangerous since thereis always the possibility of having an abrasive particle entrained and,thereby, scratching the surface. This is especially hazardous whendealing with optically precise lenses. By using only compounds that arevolatilizable at ambient or ordinary room temperatures, the need forsurface rubbing is eliminated.

Although some prior art cleaning compositions are theoreticallyvolatile, in actual practice they leave a residual film believed tocomprise dissolved and unevaporated materials or impurities on thesurface, and this film is capable of trapping dirt and dust particles.The preferred formulations of this invention however are not onlyvolatile, but also avoid leaving residual films after evaporation.

In the formulations of this invention, the alcohols used have graduatedproportional volatility rates. After the cleaning composition hascompletely spread over the lens surface, it appears that evaporationoccurs in a controlled, graduated manner. This apparent controlled rateof evaporation coupled with the use of some solvents whose vaporpressure is less than that of water avoids extensive atmosphericmoisture condensation as discrete droplets, due to evaporative surfacecooling. However, these volatile solvents dissolve the condensed waterand maintain it as a uniform surface film preventing spot formationsdueto soil concentration in the condensed droplets of water. Removal oforganic and inorganic substances is further assured by including in theformulation small amounts of a surface active agent and a greasesolvent.

Since the foregoing description and drawings are merely illustrative,the scope of the invention has been broadly stated herein and it shouldbe liberally interpreted to secure the benefit of all equivalents towhich the invention is fairly entitled.

We claim:

1. A surface cleaning composition consisting essentially of 15-50percent by weight of methanol, 0-25 percent by weight of ethanol, 25-85percent by weight of n-propyl alcohol, 1-3 percent by Weight of2-methoxy-ethanol, and 1-3 percent by weight of3,5-dimethyl-1-hexyn-3-ol.

References Cited UNITED STATES PATENTS LEON D. ROSDOL, Primary ExaminerW. E. SCHULZ, Assistant Examiner US. Cl. X.R.

106-311; 252-3 64, DIG. 10

Dated April 17, 1973 Patent No. 3 7Z8 269 Inventor(s George StephensonIt is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 1, line 40 delete "evaporatively" Column 3, line 75 change "is"to are Column 4, line 29 change "end" to and Column 5, line 55 delete"and" Column 6, line 12 change "solvent" to solvents Column 6, line 14change "condensation" to condensed Column 7, line 30 insert that-- after"composition" Column 8, line 12 change "prove" to proven Signed andsealed tnis 18th day of December 1973.

(SEAL) Attest:

EDWARD M. FLETCHER, JR. 7 Attesting Officer RENE D. TEGTD'IEYER Acting:Commissionerof Patents I FORM PO-1050 (10-69) Patent No.

Column 1, line Column 3, line Column 4, line Column 5, line Column 6,line Column 6, line Column 7, line Column 8, line (SEAL) Attest:

UNITED STATES PATENT OFFICE EDWARD M. FLETCHER, JR; Attesting; OfficerCERTIFICATE OF CORRECTION Dated April 17 1973 Inventor(s) George p ensonIt is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

delete change "evaporatively" "is" to are "end" to and "and" "solvent"to solvents "condensation" to condensed -thatafter "composition" "prove"to proven Signed and sealed this 18th day of December 1973.

RENE D. TEGTMEYER Acting; Commissioner of Patents FORM Po-10s0 (10-69)

